W83877TF Datasheet, PDF (56/154 Pages) Winbond – I/O chip disk drive adapter

W83877TF
Bit 6: This bit represents the current state of the printer's ACK signal. A 0 means the printer has
received a character and is ready to accept another. Normally, this signal will be active for
approximately 5 microseconds before BUSY stops.
Bit 5: A 1 means the printer has detected the end of paper.
Bit 4: A 1 means the printer is selected.
Bit 3: A 0 means the printer has encountered an error condition.
Bit 1, 2: These two bits are not implemented and are logic one during a read of the status register.
Bit 0: This bit is valid in EPP mode only. It indicates that a 10 µS time-out has occurred on the EPP
bus. A logic 0 means that no time-out error has occurred; a logic 1 means that a time-out error
has been detected. Writing a logic 1 to this bit will clear the time-out status bit; writing a logic 0
has no effect.
4.2.3 Printer Control Latch and Printer Control Swapper
The system microprocessor can read the contents of the printer control latch by reading the printer
control swapper. Bit definitions are as follows:
7 6 5 43 21 0
11
STROBE
AUTO FD
INIT
SLCT IN
IRQ ENABLE
DIR
Bit 7, 6: These two bits are a logic one during a read. They can be written.
Bit 5: Direction control bit
When this bit is a logic 1, the parallel port is in input mode (read); when it is a logic 0, the
parallel port is in output mode (write). This bit can be read and written. In SPP mode, this bit is
invalid and fixed at zero.
Bit 4: A 1 in this position allows an interrupt to occur when ACK changes from low to high.
Bit 3: A 1 in this bit position selects the printer.
Bit 2: A 0 starts the printer (50 microsecond pulse, minimum).
Bit 1: A 1 causes the printer to line-feed after a line is printed.
Bit 0: A 0.5 microsecond minimum high active pulse clocks data into the printer. Valid data must be
present for a minimum of 0.5 microseconds before and after the strobe pulse.
- 52 -
Publication Release Date: March 1998
Version 0.61